1. Field of the Invention
This invention relates to the field of blood banking, wherein blood is stored in tubular segments which are then pierced to obtain blood specimens for screening. This invention provides a fast and safe method of piercing which reduces the risk that technicians will come into contact with hazardous specimens. The invention also provides means for containing, diluting, mixing and dispensing the specimen.
2. State of the Prior Art
In blood banks throughout the world, specimens are routinely screened to match the donor blood with the recipient's blood. The typical way of obtaining specimens is to acquire a small quantity of the blood from the plastic tube that originally transferred blood from the donor to the blood storage bag.
After the donor has given blood, the tube connecting the donor's arm with the storage bag is partitioned into a plurality of segments, by pinching and heat sealing the tube at several locations along its length. The pinching and sealing is done while the tube is still filled with blood, and while it is still attached to the blood storage bag. Thus, the contents of the tube will be guaranteed to be the same as the contents of the bag. The segmented tube has the appearance of a series of sausage links, each link containing an identical blood specimen. Due to the heat sealing, the segments of the tube comprise separate and independent compartments of blood. It is useful to have a plurality of such independent blood-filled segments so that one can perform different tests, on the same blood, at different times. Each segment can be removed from the others by cutting it off along the heat-sealed portion, without disturbing the contents of any segment.
The present invention is concerned with the process of removing blood from one of the segments. When tests for typing or cross-matching are performed, one or more segments are torn off the chain at the pinched locations. Over time, gravity separates the blood cells from the serum. Alternatively, one can speed the separation process by centrifugation. The end of the segmented tube containing the liquid cells is cut, usually with a scissors. A few drops of the blood cells are then squeezed from one end of the segment into a test tube, diluted with saline and then transferred to other containers for analyses.
The above-described practice is hazardous because the technician often comes into contact with blood and can become infected with viruses such as HIV and hepatitis, especially if the contaminated scissors accidentally cuts the technician. Also the scissors must be cleaned between uses to avoid contamination, a practice which is time consuming and requires the consumption of cleaning preparations.
A device currently in use avoids these hazards by means of a sharp puncturing prong which is positioned inside a test tube so that the segment becomes pierced when it comes in contact with the prong. The prong is not rigidly attached to the tube, but is only suspended from the edge of the tube. The prong of this device often fails to contact the segment, and therefore fails to puncture the segment, because it is not maintained in the proper position. Furthermore, the prong is known to impede the passage of the blood because it plugs the very opening in the segment that it creates, causing rupturing of cells. To avoid these problems, the technician must perform extra steps when removing the segment from the prong. Also, the use of the above-described device requires the use of a test tube, which adds to the cost of the procedure.
Another known device provides a piercing needle inside a plastic sheath. The device is similar in configuration to the well-known needle assembly which is used to pierce and fill the typical blood collection tube. The device is located inside a test tube and its sharp cannula punctures the segment, after which blood passes through the cannula, out of the sheath, and into the test tube in which it is located. A major disadvantage of this device is that it also requires a test tube, which increases the cost of the procedure.
In both of the devices described above, a pipette is required to transfer droplets of diluted specimens from a first test tube, into other test tubes where tests are performed, thus increasing the cost and complexity of the procedure.
The present invention provides a device and method which overcome the disadvantages of the prior art described above.